Type species is Camarasaurus supremus (the originally named species, whose name means “the biggest chambered lizard”)

Other species include Camarasaurus grandis (“grand chambered lizard,” named in 1877), Camarasaurus lentus, named in 1889

Othniel Charles Marsh later named some sauropods Morosaurus grandis, but these are now considered to be Camarasaurus

There was also Camarasaurus lewisi, which was named in 1988 and originally classified as Cathetosaurus. But in 2013 another study split the two genera again

Camarasaurus synonyms include Caulodon, Morosaurus, Uintasaurus

One of the most commonly found sauropods

Lots of Camarasaurus skulls have been found

Cope wasn’t the best record keeper, and he labeled some Camarasaurus fossils (now at AMNH) with letters and numbers, to correspond with a set of dig site sketches. But he threw away the dig site sketches, so it’s not clear what he meant (some copies have been found, but not enough)

Brontosaurus was originally given a Camarasaurus skull (Brontosaurus is a diplodocid, so it’s skull was more likely elongated and narrow, and not so boxy)

Charles W. Gilmore found a nearly complete skeleton of Camarasaurus in 1925 (a young Camarasaurus, so drawings from that time depict Camarasaurus as smaller than we now know it is)

Camarasaurus is a basal macronarian, a group of sauropods that kept their heads up high and include Brachiosaurus,‭ ‬Giraffatitan, Lusotitan

Camarasaurus grandis is the oldest species

Camarasaurus lentus and Camarasaurus grandis probably co-existed for several million years, and were slightly different so probably filled slightly different ecological roles

Camarasaurus grandis disappeared, then Camarasaurus lentus disappeared, around the same time Camarasaurus supremus appeared, which may mean Camarasaurus supremus evolved from Camarasaurus lentus

Only difference between Camarasaurus supremus and Camarasaurus lentus is that Camarasaurus supremus was larger (also, it was found in the upper parts of the formation, so it’s the newest Camarasaurus)

Camarasaurus lentus could grow up to 49 ft (15 m) long

Camarasaurus supremus could grow up to 75 ft (23 m) long and weigh up to 47 tons

Had pneumatic bones, with air sacs in the vertebrae that connected to the lungs

Forelimbs were shorter than the hindlimbs

Had five toes, and sharp claws on its feet

For a while, it was thought that Camarasaurus had a second brain (had an enlarged space by the hips), but this is no longer thought to be true

Probably had a stiff, muscular neck

Probably traveled in herds or groups of families, based on two adults and a juvenile that were found to have died together, from drowning while crossing a flooded river

Probably didn’t take care of its young, like other sauropods, based on nests found with Camarasaurus eggs found in lines (not arranged nicely, and the eggs may have been laid near undergrowth so hatchlings could run for cover)

Charles Marsh at one point thought that Camarasaurus gave live birth (like sharks, which develop eggs in the body and give live birth), but there’s no evidence for this

Had a blunt snout and a squarish, arched skull

May have had a beak. No evidence has been found yet, but some Camarasaurus teeth have been found in the lower jaws that are not connected to the jaw bone exactly but were preserved in the right place (may have been because of soft tissue that kept them there); a beak would also have helped it shear through plants

Had spatulate teeth

Teeth were strong, could probably eat tough vegetation

Probably held its neck up high, and was a high browser

One Camarasaurus specimen found had evidence of soft tissue (the gums), which show that Camarasaurus probably had gums covering all but the tips of the crowns of its teeth. The specimen is nicknamed “ET” because when it was first found all you could see was a finger bone coming out of the rock

Probably did not swallow gastroliths, instead, had strong teeth that were replaced about every 62 days (so may have chewed its food)

Vegetation at the time included ferns, conifers, green algae, fungi, mosses, horsetails, cycads, and ginkoes

Other dinosaurs that lived among Camarasaurus include Diplodocus, Apatosaurus, Brachiosaurus, ornithischians such as Camptosaurus, Stegosaurus, Dryosaurus, theropods like Saurophaganax, Torvosaurus, Ceratosaurus, Ornitholestes, and Allosaurus

A partial Camarasaurus grandis skeleton found in 1992 at the Bryan Small Stegosaurus Quarry of the Morrison Formation was found to have pathologies that would have made it difficult to move its forelimb (a lesion on the bone that looks to be made of woven bone fibers). It probably healed but with a growth that would have made it difficult to forage for food and escape predators. Pathology may have been caused by an avulsion injury (part of the bone and its muscle attachment was ripped from the rest of the bone), according to McWhinney and others, which may have been because of a slip or fall, or repetitive strain (that Camarasaurus may have lived in an area of uneven ground)

A Camarasaurus pelvis found in Dinosaur National Monument in Utah shows signs of Allosaurus bites (Allosaurus did not necessarily kill the Camarasaurus, instead it may have eaten the Camarasaurus after it died)

One Camarasaurus specimen was prepared and put on exhibit at the 1933 World’s Fair, and is now on display at the Smithsonian National Museum of Natural History in Washington, D.C.

A mounted Camarasaurus, lent from the Smithsonian, was on display at the Dallas Federal Building as part of the 1960 expo to celebrate Texas’ 100th birthday

Can see a Camarasaurus at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania

Can see a Camarasaurus in situ at Dinosaur National Monument

Only two skulls left on the quarry face at Dinosaur National Monument are of Camarasaurus (can also see the neck bones of one)

Fun Fact:

Mammals were probably mostly nocturnal until dinosaurs went extinct. This may have resulted in a “nocturnal bottleneck” giving modern mammals some nocturnal features including: Large eyes that favor low light to precision, a broad range of hearing, a better sense of smell, and whiskers.

Sponsor:

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Ornithischian that lived in the Jurassic in what is now southern Africa (Lesotho)

Named by Peter Galton in 1978

Only one valid species: Lesothosaurus diagnosticus

Named for the country Lesotho, where it was found

Originally considered to be an ornithopod, but Paul Sereno suggested it could be the most primitive of known ornithischians

Had some primitive anatomy, like a partially closed hole in its pelvis by a medial wall (most dinosaurs did not have this)

Lesothosaurus has been sometimes confused with Fabrosaurus (an ornithischian from the same time and place, that was named in 1964). But only a jawbone and three teeth have been described of Fabrosaurus, so it’s hard to know for sure)

Richard Butler said in 2005 that Lesothosaurus was a basal member of Neornithischia (includes pachycephalosaurs, ceratopsians, ornithopods)

Could also be an early thyreophoran (same group as stegosaurs and ankylosaurs)

Richard Butler named a new dinosaur, Stormbergia dangershoeki, in 2005, and some scientists think it was an adult version of Lesothosaurus, which would make them synonyms. (In 2017, Baron, Norman & Barrett studied the differences between the two and found they were mostly because of their growth.)

Bipedal

About 3-6 ft (1-2 m) long

Had a small skull that was short and flat

Had large eye sockets and large cavities for the jaw muscles

Had a short, flexible neck

Had short forelimbs compared to its hindlimbs

Had five fingers on each hand (only 4 were well developed)

Had long, slender legs, small arms (hands could not really grasp things), and a slender tail

Probably was a fast runner

Had a beaklike structure

Beak was covered in keratinous material

Had leaf-shaped teeth behind the beak, and 12 fanglike teeth in front of the upper jaws

Could not chew its food, but could slice it with its beak

Omnivorous, probably (based on studies of its tooth, which found not enough wear)

Probably ate small animals and soft plants

May have been similar to a gazelle, browsing low-vegetation and running off when predators approached

May have lived in groups

In 2015, scientists CT scanned Lesotho skulls, which gave a much more detailed description of the skull and was used to refer more specimens to the genus.

These specimens were buried together, which is why scientists think they may have lived in groups

What’s for dinner? Yulong.

bwak bwak! I’m as big as dinosaur!

Yes, we’re still discovering new types of dinosaurs. A new one, called Yulong mini, apparently had offspring the size of chickens—the smallest dinosaurs ever found, according to a study in Naturwissenschaften, as cited on Discovery News.

Yulong was discovered in the Henan Province in central China, by archaeologist Junchang Lü and his colleagues. They are classified as oviraptorids, also known as “egg thieves.” However, in the 1990s, scientists came to the conclusion that these dinosaurs used other dinosaurs’ nests for brooding, instead of stealing eggs.

One interesting find with the study of Yulong is the fact that oviraptors may have been herbivores, and not carnivores, as previously thought. Additionally, Yulong babies most likely grew up without parents caring for them.

Yulong apparently looked like a chicken with a tail, though it could grow to 26 feet long. But Yulong is not an ancestor of birds, since all non-avian dinosaurs went extinct about 65 millions years ago. However, Yulong not only looked like a chicken, but it also was popular prey, and T. rex and other carnivorous dinosaurs enjoyed eating it. Too bad we’ll never know if it tasted like chicken too.